1. Field of the Invention
The present invention relates to a stamp device for forming an image on a thermal stencil paper and transferring the image to a recording paper and, more particularly, to a stamp device enabling an operator to confirm the image to be formed on the thermal stencil paper.
2. Description of the Related Art
A rubber stamp is conventionally used to print various representations such as an address and name of a person or company. Such a rubber stamp is useful and convenient in the case of repeatedly printing the same characters. Another type of printing device is a depression type stamp device employing a thermal stencil paper as described in parent U.S. patent application Ser. No. 07/811,974. This device will now be described with reference to the drawings.
FIG. 9 is a perspective view of a stamp device 1 of the parent application. The stamp device 1 includes a keyboard 10, a body 11, a stamp 12, and a liquid crystal display (which will be hereinafter referred simply to as a "display") 14 having the predetermined number of display columns. The keyboard 10 includes a character key 42 for inputting characters such as Japanese "kana" character and alphabet, and also includes various function keys such as a stamp original creating key.
As shown in FIG. 8 which is a cross section taken along the line F--F in FIG. 9, the body 11 is constituted of a stencil paper holding section 15, an original creating section 16, a stamp holding section 17, and a control section 18. The stamp 12 is constituted of a grip 13, a stamp body 28, a spring 29, and an ink pad 30. The original creating section 16 includes a thermal head 19 as heating means. The thermal head 19 is pressed against a platen roller 20. A thermal stencil paper (which will be hereinafter referred simply to as a "stencil paper") 24 is drawn by a stencil paper drawing roller 21, and is fed by stencil paper feeding roller pairs 22 to between the thermal head 19 and the platen roller 20.
After the stencil paper 24 is thermally perforated by the thermal head 19, it is further fed by the stencil paper feeding roller pairs 22 and stencil paper feeding rollers 23 to under the stamp 12. The stamp body 28 of the stamp 12 is secured to a supporting member (not shown) with a gap 27 defined between the ink pad 30 and the stencil paper feeding rollers 23 in the stamp holding section 17. The thermally perforated stencil paper 24 is fed by the stencil paper feeding roller pairs 22 and the stencil paper feeding rollers 23 by a predetermined amount so as to come to just under the ink pad 30.
The stencil paper 24 is formed by bonding a thermoplastic film to a porous carrier. The stencil paper 24 is used under the condition where the thermoplastic film side is adapted to contact the thermal head 19. As shown in FIGS. 10 and 11, a frame 25 is bonded onto the stencil paper 24.
The thermal head 19 has a head body provided with a heat generating element array. The heat generating element array consists of a plurality of heat generating elements, e.g., 96 heat generating elements are arranged in line in the stamp device 1. These heat generating elements are arranged adjacent to each other in a direction perpendicular to a feeding direction of the stencil paper 24. The heat generating element array is driven at a predetermined timing in accordance with feed of the stencil paper 24 to thereby thermally perforate the stencil paper 24 according to data input from the keyboard 10.
A control system of the stamp device 1 will be described with reference to the block diagram shown in FIG. 12. The keyboard 10 is connected to an input interface 58 in a microcomputer 56. The input interface 58 is connected through a bus line 60 to a CPU 62, a ROM 64, a RAM 66, a character generator (CG-ROM) 68 for thermal perforation of the stencil paper 24, a character generator (CG-ROM) 69 for display, and an output interface 70.
The ROM 64 includes a program memory 71 previously storing a program for controlling the whole operation of the stamp device 1 and a dictionary memory 72 to be used for kana/kanji conversion where Japanese "kana" characters are converted into Chinese "kanji" characters or the like. The RAM 66 includes an input buffer 73 for storing data input from the keyboard 10, a thermal perforation buffer 74 and a shift register 75 for storing data for thermal perforation of the stencil paper 24, and other necessary counters and registers.
The CG-ROM 68 serves to generate dot patterns according to code data of characters input, and the CG-ROM 69 serves to generate dot patterns to be displayed on the display 14.
A head driving circuit 76, a motor driving circuit 77 and a display driving circuit 78 are connected to the output interface 70. The thermal head 19, paper feeding motors 32 and the display 14 are connected to the circuits 76, 77 and 78, respectively.
The operation of creating a stamp original by the stamp device 1 will now be described with reference to the flowchart shown in FIG. 13. When power is applied to the stamp device 1, the buffers, registers, etc. in the RAM 66 are initialized, and the others are also initialized in step S1 (which will be hereinafter referred simply to as "S1" and the other steps will also similarly referred). Then, a string of characters is input from the keyboard 10 with the characters displayed on the display 14. That is, data for thermal perforation is input from the character key 42, and it is stored into the input buffer 73 in S2, S3 and S4. At the same time, in S5, the characters corresponding to the thermal perforation data are displayed on the display 14 through the CG-ROM 69.
When the stamp original creating key is depressed, S7 is executed after S2 and S6, in which the dot patterns generated in the CG-ROM 68 according to the code data input are developed in the thermal perforation buffer 74. Then, the program proceeds to S8 in which the dot patterns developed in the thermal perforation buffer 74 are transferred by every row of dots to the shift register 75 to thermally perforate the stencil paper 24 in accordance with the row of dots. In S9, it is determined whether or not all the thermal perforation data have been output to the stencil paper 24, and the steps of S8 and S9 are repeated to finally obtain the result of thermal perforation constituted of 96 dots over the length of the heat generating element array. At this time, the thermally perforated stencil paper 24 is fed by the stencil paper feeding roller pairs 22 and the stencil paper feeding rollers 23 in a direction D shown in FIG. 8.
When the grip 13 of the stamp 12 is depressed toward the stencil paper 24 against the spring 29, the ink pad 30 comes into contact with the stencil paper 24. Owing to the viscosity of ink impregnated in the ink pad 30, the stencil paper 24 adheres to the ink pad 30. Then, the stamp 12 is pulled out of the stamp holding section 17 of the body 11 of the stamp device 1 by holding the grip 13. Thereafter, the grip 13 of the stamp 12 is depressed toward a recording paper 35 in a direction H shown in FIG. 14, and the ink impregnated in the ink pad 30 is supplied to the stencil paper 24. As a result, a part of the ink at a thermally perforated portion only of the stencil paper 24 is allowed to reach the recording paper 35, thus forming an image on the recording paper 35 as shown in FIG. 15.
However, resolution of the liquid crystal display is greatly lower than that of the thermal head. Accordingly, when an operator intends to confirm a stamp image formed after inputting data from the keyboard, the stamp image cannot be clearly confirmed on the liquid crystal display. So, the operator is obliged to actually print the input data as a sample or view the perforation image on the stencil paper attached to the stamp. If the stamp image is not satisfactory in the sample or as viewed in the perforation, the stencil paper is obliged to be wasted.